Process for the production of tetrahydrofuran and gammabutyrolactone

Abstract

A two-stage process for producing tetrahydrofuran and gammabutyrolactone in varying proportions from maleic, succinic anhydride or fumaric acid esters, by vapor phase hydrogenation. The first stage occurs on a copper-based catalyst to produce a mixture of tetrahydrofuran, gammabutyrolactone and butanediol. The second stage occurs on an acidic silica rich silica-alumina type catalyst to convert butanediol to tetrahydrofuran.

What is claimed is:  
     
       1. A process for the production of tetrahydrofuran (THF) and gammabutyrolactone (GBL), comprising vapour phase selective hydrogenation of maleic anhydride, succinic anhydride and/or fumaric acid esters, wherein the hydrogenation takes place in first and second sequential stages, wherein the hydrogenation in the first stage takes place on a copper based catalyst, and the hydrogenation in the second stage takes place on an acidic silica-alumina catalyst that is rich in silica and; 
       discharging a stream comprising tetrahydrofuran and gammabutyrolactone from the second stage.  
     
     
       2. A process according to claim  1 , wherein the ester alkyl component contains from 1 to 4 carbon atoms. 
     
     
       3. A process according to claim  1  wherein the hydrogenation operating pressure ranges between 3 and 40 bars, and operating temperature ranges between 180 and 280° C. 
     
     
       4. A process according to claim  1 , wherein the hydrogenation operating pressure ranges between 15 and 25 bars. 
     
     
       5. A process according to claim  1  wherein the hydrogen to ester ratio in the reactor ranges between 100/1 and 600/1. 
     
     
       6. A process according to claim  5 , wherein the hydrogen to ester ratio in the reactor ranges between 200/1 and 400/1. 
     
     
       7. A process according to claim  1  wherein the ratio of produced gammabutyrolactone (GBL) to tetrahydrofuran (THF) ranges between 70/30 and 40/60. 
     
     
       8. A process according to claim  1 , wherein in the first hydrogenation stage the catalyst is copper-zinc oxide or of the copper chromite type and it is coupled in the second stage with a catalyst rich in silica. 
     
     
       9. A process according to claim  1  wherein a catalyst employed in the second stage is an acidic mordenite or zeolite. 
     
     
       10. A process according to claim  8 , wherein the copper chromite is stabilised. 
     
     
       11. A process according to claim  5 , wherein in the second stage the catalyst has a specific surface area ranging between 50 and 800 m 2 g −1 . 
     
     
       12. A process according to claim  9  wherein the apparent bulk density (ABD) of the catalyst is 0.65 and its surface area equals 450 m 2 gr −1 . 
     
     
       13. A process according to claim  1  wherein the catalyst in the second stage contains at least 80% silica. 
     
     
       14. A process according to claim  1 , wherein the vapour phase mixture containing hydrogen and ester flows on the catalysts with a liquid hourly space velocity that ranges between 0.1 and 0.5 hr −1 . 
     
     
       15. A process according to claim  1 , wherein the vapour phase travels on the reaction second stage catalyst with a space velocity which is 1.5 to 10 times higher than that on the catalyst of the reaction first stage. 
     
     
       16. A process according to claim  1 , wherein the hydrogen rich recycle stream is washed downstream from the reaction with a butyrolactone rich stream, to remove the steam present in the recycle gas.